About 4,500 million years ago, a Mars-sized body collided with the newly formed Earth, creating our own moon. Now, a team of scientists suggests that this giant impact had an even bigger impact: The impact left behind mysterious bubbles in the Earth’s interior. It helped usher in plate tectonics – The geological process that fuels earthquakes, volcanoes and generally allows life to exist on our planet.
The idea was developed using computer models in a new study published in magazine Geophysical Research Lettersis an attempt to answer one of the fundamental questions about our planetary home.
We live on the only known planet whose surface is made of rocky plates that slide and collide with each other in boundary regions when the superheated interior moves. This subterranean drama usually goes unnoticed on the scale of human time, except when an earthquake or volcanic eruption occurs. But most experts agree that this process is absolutely essential to life as we know it, because it helps the planet cycle carbon, which is important for maintaining a habitable climate.
What experts don’t agree on is the origin of plate tectonics.
Hey New scientific article It is based on an earlier idea that attempts to explain a geological mystery. For decades, geologists have speculated that mysterious bubbles exist deep within the Earth’s mantle that were discovered through seismic images. These huge, dense bubbles appear to be made of a different material than the surrounding mantle, raising questions about what they are and how they formed.
hypothesis – Published in magazine nature last year – It provides an explanation, but it also raises some questions. This indicates that after the body that formed the Moon collided with our planet, pieces of that body ended up intact inside the Earth.
The new study takes this idea a step further: About 200 million years after the impact, these submerged bubbles may have helped form hot plumes deep within the Earth, disrupting the newly formed surface, rupturing the crust and allowing the rings to form. A process called subduction.
This process, say the study authors, may explain the fact that the oldest minerals on Earth are zircon crystals that appear to have sunk more than 4 billion years ago. Furthermore, they suggest that it may have contributed to the emergence of modern plate tectonics.
“The giant impact not only caused the Moon to exist, if that were the case, but it also created the initial conditions for our Earth“Qian Yuan, a geoscientist at the California Institute of Technology (USA) and one of the study’s authors, said: condition.
Time is almost impossible to know?
Geologists who were not involved in the research say that this model is interesting, but it raises a number of questions.
Taras Geria, a geoscientist at the Federal Institute of Technology in Zurich (Switzerland), said: e-mailThe idea of an initial subduction phenomenon caused by powerful mantle plumes shortly after the collision that formed the Moon is credible and is supported by models and some geochemical data. But he added that he was unsure whether this would lead to modern plate tectonics or whether it would lead to rapid global recycling of the entire crust, similar to what might happen on the inhospitable planet Venus.
Michael Brown, a geologist at the University of Maryland, said it’s not clear how a circular subduction zone would lead to global plate boundaries and the mosaic of lithospheric plates found in modern plate tectonics.
“We have to take into account that there is not enough evidence to know the tectonic situation in the Archaic era“He also said that it was an eon that lasted between 4,000 and 2,500 million years Michael brown. “Therefore, from a philosophical point of view, it is almost certainly unknown and unknown. I think sometimes the point is missed.“
I wrote. Mark Harrison, a research professor at the University of California, Los Angeles, recently wrote an article entitled “We don’t know when plate tectonics began“. He questioned the model’s assumptions, pointing to geochemical discrepancies that cast doubt on the giant impact theory itself.
“If we didn’t have plate tectonics, we wouldn’t be having this conversation, because our species wouldn’t have existed.“He said sign Harrison. “The best I can tell people is that my generation (…) failed to solve the most interesting question in science, which is how and under what conditions life arose.“
For future scientists sign Harrison He has a message: “We leave you a small wrapped gift.“
“Friendly zombie fanatic. Analyst. Coffee buff. Professional music specialist. Communicator.”
